Severe carotid stenoses

Blaser T, Hofmann K, Buerger T, Effenberger O, Wallesch CW, Goertler M. Risk of stroke, transient ischemic attack, and vessel occlusion before endarterectomy in patients with symptomatic severe carotid stenosis. Stroke 2002 33 1057-1062. 

MasJL, ChatellierG, Beyssen B. Carotid angioplasty and stenting with and without cerebral protection clinical alert from the Endarterectomy Versus Angioplasty in Patients With Symptomatic Severe Carotid Stenosis (EVA-3S) trial. Stroke 2004 35 el8-20. 

Can simple clinical features be used to identify patients with severe carotid stenosis on Doppler ultrasound Journal of Neurology, Neurosurgery and Psychiatry 66 16-19... 

There were relatively few developments for the next 70 years. However, in 1946, a Portuguese surgeon, Cid Dos Santos, introduced thromboendarterectomy for restoration of flow in peripheral vessels (Dos Santos 1976). The first successful reconstruction of the carotid artery was performed by Carrea, Molins and Murphy in Buenos Aires in 1951 (Carrea et al. 1955). However, this was not an endarterectomy. Rather they performed an end-to-end anastomosis of the left external carotid artery and the distal internal carotid artery (ICA) in a man aged 41 years with a recently symptomatic severe carotid stenosis. 

As a result of the large randomized controlled trials, it is now clear that endarterectomy of recently symptomatic severe carotid stenosis almost completely abolishes the high risk of ischemic stroke ipsiiaterai to the operated artery over the subsequent two or three years (see Ch. 27 for detailed discussion of the selection of patients for surgery). Moreover, this effect is durable over at least 10 years (European Carotid Surgery Trialists Collaborative Group 1991, 1998 Mayberg et al. 1991 North American Symptomatic Carotid Endarterectomy Trial Collaborators 1991 Barnett et al. 1998 Rothwell et al. 2003). Indeed, the ipsiiaterai stroke risk becomes so low that presumably both embolic and low-flow strokes are being prevented (Fig. 25.1). 

It is conceivable that patients with impaired cerebral reactivity and raised oxygen extraction fraction are at particular risk of stroke without surgery, and that this impairment can be corrected by carotid endarterectomy, but the studies have been too small to be sure (Schroeder 1988 Naylor et al. 1993b Yonas et al. 1993 Hartl et al. 1994 Yamauchi et al. 1996 Visser et al. 1997 Silvestrini et al. 2000 Markus and Cullinane 2001). Also, we do not know what proportion of strokes in patients with recently symptomatic severe carotid stenosis are actually caused by impaired cerebral reactivity, either as a direct result of low flow or perhaps indirectly as a result of an inadequate collateral circulation to compensate for acute arterial occlusion if it should occur. Nor do we know whether the risk of surgery is higher in these patients and so whether, on balance, carotid endarterectomy will indeed reduce stroke risk any more than in those without impaired reactivity. 

Endarterectomy of severe carotid stenosis to improve collateral blood flow, via the circle of Willis, to the basilar artery distal to vertebral or basilar artery stenosis or occlusion Resection and anastomosis Resection and reimplantation... 

Recurrent transient neurological deficits also occur commonly in patients with ICA stenosis. These deficits generally last for less than 3 min and include transient monocular blindness as well as transient hemispheric neurologic deficits. Their pathologic basis is unknown, though in some cases of transient monocular blindness there is evidence of low flow (the box car appearance of red cell clumps separated by clear space) in the retinal arterioles. The retina may also contain highly refractile cholesterol emboli called Hollenhorst plaques. In many instances of severe carotid stenosis or occlusion, the intracranial collateral flow is sufficient to perfuse the brain and prevent ischemia [17]. 

Calculation of CBF requires knowledge of the AIF, which in practice is estimated from a major artery, assuming that it represents the exact and only input to the tissue voxel of interest, with neither delay nor dispersion. There are several clinical situations, however, where the AIF TDC will lag, and the tissue TDC will lag behind the AIF curve ( delay ). AIF delay can be due to extracranial causes (atrial fibrillation, severe carotid stenosis, poor left ventricular ejection fraction) or to intracranial causes (proximal intracranial obstructive thrombus with poor collaterals). Moreover, in such cases, the contrast bolus forming the AIF can spread out over multiple pathways proximal to the tissue ROI ( dispersion ). Delay and dispersion can result in grossly underestimated CBF and overestimated MTT [125,147,148]. 

Silvestrini, M., Troisi, E., Matteis, M., Cupini, L. M., and Caltagirone, C. (1996) Transcranial Doppler assessment of cerebrovascular reactivity in symptomatic and asymptomatic severe carotid stenosis. Stroke 27,970-973. 

Mrc European carotid surgery trial interim results for symptomatic patients with severe (70-99%) or with mild (0-29%) carotid stenosis. European Carotid Surgery TriaUsts Collaborative Group. Lancet 1991 337 1235-1243. 

Gasecki AP, Eerguson GG, EUasziw M, Clagett GP, Pox AJ, Hachinski V, Barnett HJ. Early endarterectomy for severe carotid artery stenosis after a nondisabling stroke Results from the North American symptomatic carotid endarterectomy trial. J Vase Surg 1994 20 288-295. 

All these antioxidative and anti-atherogenic effects of pomegranate polyphenols were clearly demonstrated in vitro, as well as in vivo in humans, and in the atherosclerotic apolipoprotein E-deficient mice. Dietary supplementation of pomegranate juice rich in polyphenols to patients with severe carotid artery stenosis or to atherosclerotic mice resulted in a significant inhibition in the development of the... 

Fig. 5.13a,b. Detailed depiction of a rather complex carotid stenosis with several sharp plaques and an ulceration (arrow) on CE-MRA (b) to an extent matching DSA (a)... 

Nakano S, Yokogami K, Ohta H et al (1995) CT-defined large subcortical infarcts correlation of location with site of cerebrovascular occlusive disease. AJNR 16 1581-1585 Neumann-Haefelin T, Wittsack HJ, Fink GR et al (2000) Diffusion- and perfusion-weighted MRI. Influence of severe carotid artery stenosis on the DWI/PI mismatch in acute stroke. Stroke 31 1311-1317... 

Fig. 10.4. These T2-weighted (top) and diffusion-weighted (bottom) scans were taken of an 81-year-old man with a fall 10 days previously that was followed by difficulty using his left leg, confusion and slurred speech. The diffusion-weighted image confirms multiple acute lesions in the right hemisphere and carotid imaging confirmed severe right carotid stenosis.

A similar trade-off between diagnostic accuracy and risk is necessary when imaging the carotid bifurcation in patients with TIA or ischemic stroke. Performing intra-arterial catheter angiography in everyone is clearly unacceptable because of the risks and cost. Fewer than 20% of patients will have an operable carotid stenosis even if only those with cortical rather than lacunar events are selected (Hankey and Warlow 1991 Hankey et al. 1991 Mead et oL 1999). Coirfining angiography to patients with a carotid bifurcation bruit will miss some patients with severe stenosis and still subject too many with mild or moderate stenosis to the risks. Nor will a combination of a cervical bruit with various clinical features do much better (Mead et al. 1999). 

Although duplex sonography is non-invasive and widely available, there are some difficulties that any ultrasound service must deal with (Box 12.1). Nonetheless, with stringent quality control and ideally with confirmation of stenosis by an independent observer, duplex sonography is now the most common way that carotid stenosis severe enough to warrant surgery is diagnosed (Chappell et al. 2006). 

However, without formal risk models, clinicians are often inaccurate in assessment of risk in their patients (Grover et al. 1995). Moreover, the absolute risk of a poor outcome for patients with multiple specific characteristics cannot simply be derived arithmetically from data on the effect of each individual characteristic such as age or severity of illness that is, one cannot simply multiply risk ratios for these characteristics together as if they were independent. Even if one could, it would still be rather complicated. In a patient with symptomatic carotid stenosis, for example, what would the risk of stroke without endarterectomy be in a 78-year-old (high risk) female (lower risk) with 80% stenosis who presented within two days (high risk) of an ocular ischemic event (low risk) and was found to have an ulcerated carotid plaque (high risk) ... 

Fig. 18.2. The absolute risk reduction (ARR) at five years of ipsilateral ischemic stroke (top) and any stroke or death (bottom) with surgery in European Carotid Surgery Tria centers in which the median delay from last symptomatic event to randomization was <50 days (fast centers) compared with centers with a longer delay (slow centers) (Rothwell 2005a). Data are shown separately for patients with moderate (50-69%) and severe (70-99%) carotid stenosis. Cl, confidence interval.

Mead GE, Lewis SC, Wardlaw JM, Dennis MS, Warlow CP (2000). Severe ipsilateral carotid stenosis in lacunar ischaemic stroke innocent bystanders Journal of Neurology 249 266-271... 

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